1. Field of Invention
The invention relates to cleaners for optical connectors. More specifically, this invention relates to an optical connector cleaner that uses planetary cleaning motions.
2. Description of the Related Art
Connector cleaning has recently become recognized as an important issue by the Fiber Optic Telecommunications Industry. Major suppliers, operators, original equipment manufacturers (OEMs), and others have learned and recognized that a clean connector is critical to optimal and acceptable performance of optical components, subsystems, and systems. For example, the light-carrying core diameter of the most popular single mode optical fiber, the SMF-28e® by Corning Incorporated, is only 8 microns, meaning that any contamination at the core is likely to have a significant and potentially deadly effect on the light-carrying and light-conveying capacity of that connector.
Several major Original Equipment Manufacturers (OEM's) have recently determined that a very large portion of their customer complaints, field service calls, return of materials authorizations (RMAs), and repairs are traceable to contaminated connectors. Numerous anecdotal reports characterize contaminated connectors as uniformly responsible for between 30 and 40% of all RMAs and customer complaints. Considering that the industry standard Telcordia GR-2923-CORE (“Generic Requirements for Optical Fiber Cleaning Products”), as well as many other requirements and specifications referring to Telcordia GR-2923-CORE, require pre-installation connector cleaning, it becomes clear that a solution to this problem is required, valuable, and as yet unavailable. Traditional and currently available solutions are not adequate.
The perimeter of the 2.5 millimeter ferrule end face to be cleaned as used in the popular SC, FC, ST, and E-2000™ fiber optic connectors is about 8 millimeter, while the perimeter in the 1.25 millimeter ferrule end face used in the MU and LC fiber optic connectors is about 2 millimeter. For this reason, the edge in the small form factor 1.25 millimeter ferrule presents a much sharper edge imparting a much greater force per area. For instance, when cleaning a SFF connector, the 1.25 millimeter diameter connector used in the popular MU or LC connectors with traditional and currently available products, the SFF connector damages the cleaning sheet. Such damage causes additional contamination and, consequently, the SFF connector does not become uniformly clean as required. In the case of the large form factor connectors, the 2.5 millimeter diameter connector does not uniformly clean in one swipe. Additionally, these cleaners cannot clean the small and large form factor while also cleaning new industry standard connectors such as the multi-fiber connectors which are much larger in width. It is important to note that the general requirements for qualifying a connector cleaning product or process include proof of ability to clean: a) graphite powder; b) “Arizona Road Dust,” an industry defined standard; c) lint; d) finger oil; e) liquid vegetable oils, such as Wesson® Oil; f) simethicone; g) water; h) alcohol; and i) salt water.
Thus it is desirable for an optical connector cleaning product to be able to clean both the 2.5 millimeter and 1.25 millimeter ferrule end faces without damaging the cleaning surface or the surface of the fiber or connector, and clean all these constituents, without the use of chemicals, solvents, or complex systems or procedures.
The present inventors have learned that polishing the connectors themselves during the manufacturing process, that a “planetary motion” around the connector endface is far superior to a linear motion across the ferrule and fiber endface. Earlier patents describe the method and benefits of the planetary motion in the polishing of ferrule and fiber end faces. For example, U.S. Pat. No. 5,463,709 and U.S. Pat. No. 5,559,916 both describe a method for planetary polishing motion and highlight the basis for superior polishing of the fiber/ferrule endface geometry. The present inventors have found that planetary motion polishing provides a superior method for controlling endface geometry, limiting scratches, preserving the fiber micro-geometry, and generally producing an endface that is substantially scratch-free and clean. Recent testing by the present inventors has confirmed that the use of a planetary motion provides similar benefits also true in the case of connector cleaning.
Connector cleaners have been traditionally designed such that the cleaning motion is linear along a single axis. Examples of single-axis linear motion connector cleaners include the CLETOP® reel cleaner from NTT-ME Corporation (U.S. Pat. No. 5,117,528), the OPTIPOP R reel cleaner from NTT Advanced Technology Corporation, the OPTIPOP C card cleaner also from NTT Advanced Technology Corporation (U.S. Pat. No. 6,681,437), the FiberSwiper® car cleaner from Neptec Optical Solutions, Incorporated, and others. Testing within the fiber optic has found these tools and methods wanting with regard to industry standards, such as Telcordia GR 2923-CORE. Most of these were developed before the advent, in the late 1990s, of the Small Form Factor (SFF) connector, such as the MU or LC fiber optic connectors licensed by NTT Advanced Technology Corporation and Lucent respectively, and do not address the cleaning needs of this now very popular connector.
One of the challenges in using a cleaner with single-axis linear slots is that they require the hand to impart a twisting motion on the connector as the connector is dragged along the slot. Maintaining a uniform twisting motion while linearly sliding the connector within the slot is difficult and not completing a twisting motion during the entire travel down the slot generally results in an inferior cleaning action. Traditional slot based cleaners do not provide for nor allow a circular or planetary motion other than this twisting. The product literature and use instructions very clearly instruct as to the importance of this awkward twisting motion. The traditional slit geometry, seen in the OPTIPOP C, the OPTIPOP R, the CLETOP®, and the FiberSwiper®, does not allow a planetary or angular motion and thereby suffers a significant shortcoming in this regard.
Another challenge in using SFF connectors with single axis linear slot connector cleaners is that as the operator attempts to use a twisting motion, the front edge of the connector, which is generally sharp, often digs into the fabric. When digging into the fabric, the connector tears fibers, creates contamination, and raises the connector endface so that cleaning is not only insufficiently accomplished, but may result in further contamination of the endface.